Which of the following has highly acidic hydrogen?

A solution of two miscible liquids showing negative deviation from Raoult's law will have :

Consider the following complex ions

$$\begin{aligned} & \mathrm{P}=\left[\mathrm{FeF}_6\right]^{3-} \\ & \mathrm{Q}=\left[\mathrm{V}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+} \\ & \mathrm{R}=\left[\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+} \end{aligned}$$

The correct order of the complex ions, according to their spin only magnetic moment values (in B.M.) is :

Choose the polar molecule from the following: